A viewer’s guide to Election Night 2012

The pundits are predicting a late night before we know who’s won the presidential election.

But you may not have to wait until the wee hours of the morning to learn who Americans chose to lead the country or run the Congress.

By looking at key races in states with early poll closing times, it’s possible to glean some important clues as to whether the American people are delivering a clear verdict in the presidential and congressional elections – or if the final results won’t be know until Wednesday morning or later.

A rule of thumb: The later we go before knowing the winner, the better it is for the insurgents — Republican presidential nominee Mitt Romney, Senate Republicans and House Democrats.

Here is an hour-by-hour viewer’s guide to Election Night 2012 showing you which results to watch to get an early glimpse of national trends:

Romney should win these states easily, but the TV networks won’t project a victor until all polls close at 7 p.m. EST. A Romney blowout in Indiana is a bad sign for Obama.

The Indiana Senate race is vital to Republican chances of capturing the Senate. If Republican Richard Mourdock squanders his early lead in an error-plagued campaign to replace GOP veteran Richard Lugar, it would complicate Republicans’ chances of gaining the four seats needed to ensure Senate control.

7 p.m. EST (70 electoral votes)
Key state: Virginia, Florida (most)

Two vital states to Romney’s chances start counting ballots at this hour. If Romney loses, it’s almost impossible for him to reach 270 electoral votes. If Obama is trailing, it could be a late night in front of the TV. Watch for reports about turnout in the Washington, D.C., suburbs — Obama’s stronghold.

In Florida, the TV networks won’t project a winner until polls close in the state’s western panhandle at 8 p.m. EST. One twist: Republican counties tend to report early, so don’t make statewide assumptions based on the first returns. (Remember 2000.) Watch the returns in Florida’s I-4 corridor, anchored by Tampa and Orlando.

Key Senate race: The tight contest between Republican George Allen and Democrat Tim Kaine for the seat being vacated by retiring Democrat Jim Webb. Bellwether House races: troubled incumbents John Barrow, a Georgia Democrat, and Allen West, a Florida Republican.

7:30 p.m. EST (38 electoral votes)
Key states: Ohio, North Carolina

If Romney doesn’t win Ohio, where he’s been trailing in almost every pre-election poll, it could be a long night for the challenger. Obama has remained stubbornly competitive in North Carolina, a must-win state for Romney. If the networks quickly project a Romney triumph in North Carolina, that’s a positive sign for Republicans.

North Carolina gives us an important clue about Democrats’ chances of netting the 25 House seats needed to win a majority. If two embattled Democrats, Reps. Larry Kissell and Mike McIntyre, are defeated, it’ll be almost impossible for Nancy Pelosi & Co. to dig themselves out of the hole. Another key contest: Ohio’s rare incumbent vs. incumbent between Republican Jim Renacci and Democrat Betty Sutton in the redrawn 16th District.

In the Senate, an upset win by Ohio Republican Josh Mandel would signal a national GOP tide.

Polls close in 16 states and the District of Columbia at this hour, but the ones to watch are New Hampshire and Pennsylvania. Romney invested heavily in the Keystone State last week in an attempt to pull an upset, and has scheduled an Election Day stop there. If the former Massachusetts governor is hanging tight or winning, it’s good news for the GOP nominee.

An Obama win in the Granite State could be a sign of things to come in other swing states such as Iowa and Nevada.

Key Senate races to watch: To protect their majority, Democrats can’t afford to lose incumbents Bob Casey of Pennsylvania or Claire McCaskill of Missouri, who faces controversial Republican congressman Todd Akin. The most endangered Senate incumbent in the nation is Massachusetts Republican Scott Brown. If he loses, it could be evidence of Obama coattails in strong Democratic states.

To regain the House majority, Democrats need to defeat a boatload of endangered Republican incumbents, including Francisco “Quico” Canseco of Texas, Charlie Bass of New Hampshire, and Joe Walsh and Bob Dold of Illinois. Democrats also can’t afford to lose embattled western Pennsylvania Rep. Mark Critz.

Four of the 12 top presidential battlegrounds are among the 14 states with polls closing at this hour. If Romney has already lost in either Ohio or Virginia, he’ll need an upset win in Michigan, Wisconsin, which hasn’t picked a Republican for president since Ronald Reagan, or Minnesota, which has voted Democratic every election since 1972.

In Colorado, an estimated 80 percent of voters have already cast early ballots. Republicans expect to win here, so an Obama lead would be devastating to the GOP. Warning: Up to 10 percent of Colorado ballots often are not counted on election night, so the winner may not be clear by dawn Wednesday if the race is tight.

The key Senate contest is the race to replace Arizona Republican Jon Kyl between Republican Rep. Jeff Flake and Democrat Rich Carmona, the U.S. surgeon general under President George W. Bush. If Democrats hope to gain ground in the Senate, it would come here.

10 p.m. EST (21 electoral votes)
Key states: Iowa and Nevada

The final battleground states to start counting votes will be Iowa and Nevada, where recent polls show Obama in the lead. If Romney wins both of these states, it’s a sign of a tight Electoral College finish. If Obama sweeps, it increases the pressure on Romney to carry Michigan, Pennsylvania and Wisconsin.

Republicans are counting on a pro-Romney surge in Montana to unseat the most endangered Democrat in the Senate, Jon Tester.

11 p.m. EST (85 electoral votes)
Key state: California

No drama at the presidential level at this hour. Obama will take 78 electoral votes from California, Hawaii, Oregon and Washington. Idaho and North Dakota are safe Romney country.